Median Nerve

Abstract

The median nerve (C5, C6, C7, C8, and T1) is formed by contributions from the medial and lateral cords in the axilla. It courses anterior to the axillary and then brachial arteries. It enters the cubital fossa anterior to the brachialis and deep to the bicipital aponeurosis (lacertus fibrosus ). It gives off its first branches in the upper forearm. It supplies most of the flexor muscles of the forearm: pronator teres , flexor carpi radialis , palmaris longus , and flexor digitorum superficialis (sublimis). The anterior interosseous nerve (AIN ) comes off the lateral aspect of the median nerve and supplies the flexor pollicis longus , lateral half of flexor digitorum profundus , and pronator quadratus . It has no cutaneous distribution. The median nerve courses between the two heads of pronator teres and then the two heads of flexor digitorum superficialis. It then enters the carpal tunnel with the flexor tendons under the flexor retinaculum (transverse carpal ligament ). The palmar cutaneous branch typically arises proximal to the wrist and courses superficial to the flexor retinaculum. In the hand, the median nerve gives off the palmar recurrent branch that supplies the muscles of the thenar eminence: flexor pollicis brevis , abductor pollicis brevis , and opponens pollicis . It also supplies the lateral two lumbrical muscles and then divides into digital cutaneous branches that supply the palmar surface of the lateral three and half fingers and the dorsal surface of their distal phalanges.